Calcium |
Synonyms: None
Symbol: Ca
Atomic mass: 40.078 g/mol
Element number 20 in the Periodic Table. Valence number: 2. Electronegativity: 1.00
MP= 839+/-2 o C; BP= 1484 o C; density: 1550 kg/m3; CAS-number: 7440-70-2;
Calcium is an alkaline earth metal. The concentration of calcium inside and outside the cell is approximately 10-6 and 10-3M respectively. A range of biochemical and physiological responses is activated when calcium is let into the cells or by release of calcium from intracellular organelles. In the cell transport systems continuously re-establish the gradient of calcium ions across the cell or organelle membranes. Examples of processes where calcium influx is important: Muscle contraction, release of hormones, release of neurotransmitters, regulation of enzymes, blood coagulation and incorporation as an element in bone mass. The absorption of calcium from the gastro intestinal tract is facilitated by 1,25-dihydroxy form of vitamin D2. A complex system regulates the storage and mobilization of calcium e.g. by the parathyroidea hormone, vitamin D, calcitonin, calsequestrin and osteocalcin.
www.BioSite.dk 22/11,09